Acute Kidney Injury Evaluation Quiz
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Questions and Answers

Which condition is NOT typically associated with pre-renal azotemia?

  • Vomiting
  • Exposure to Nephrotoxins (correct)
  • Diarrhea
  • Blood Loss

    • What is a key physical sign indicating pre-renal azotemia?

  • Elevated blood urea nitrogen
  • Proteinuria
  • Microscopic hematuria
  • Decreased skin turgor (correct)

    • Which class of medications is recognized for potentially inducing pre-renal azotemia?

  • Antibiotics
  • NSAIDs (correct)
  • Statins
  • Beta-blockers

    • Which type of Acute Kidney Injury is characterized by intrinsic damage to the kidneys?

    <p>Intrinsic Renal</p> Signup and view all the answers

    What is an essential step in the evaluation of Acute Kidney Injury?

    <p>Biochemical tests of renal function</p> Signup and view all the answers

    What urine osmolality measurement is indicative of pre-renal acute kidney injury (AKI)?

    <p>Urine Osmolality &gt; 500 mOsm/kg</p> Signup and view all the answers

    In what condition would you expect urine sodium levels to exceed 20 mmol/L?

    <p>Acute Tubular Necrosis (ATN)</p> Signup and view all the answers

    What finding is often associated with a poorer prognosis in acute kidney injury?

    <p>Oliguria (low urine output)</p> Signup and view all the answers

    What is the typical urine osmolality to serum osmolality ratio in acute tubular necrosis?

    <p>Less than 1.3</p> Signup and view all the answers

    Which of the following is NOT a typical finding in pre-renal acute kidney injury?

    <p>Muddy brown casts in urine microscopy</p> Signup and view all the answers

    What is a common cause of acute kidney injury (AKI) that requires careful monitoring?

    <p>Drugs with nephrotoxic potential</p> Signup and view all the answers

    Which of the following physical signs is indicative of systemic vasculitis with glomerulonephritis?

    <p>Palpable purpura</p> Signup and view all the answers

    Which of the following symptoms would likely indicate ureteric obstruction?

    <p>Colicky flank pain radiating to the groin</p> Signup and view all the answers

    What function is primarily carried out by the glomeruli in the kidneys?

    <p>Retention of red blood cells</p> Signup and view all the answers

    The presence of proteinuria is most closely related to which of the following?

    <p>Integrity of the glomerular filtration barrier</p> Signup and view all the answers

    In assessing tubular integrity, which test is less commonly performed compared to tests of glomerular function?

    <p>Glycosuria</p> Signup and view all the answers

    Which test results would most likely provide insights into acid-base regulation of the kidneys?

    <p>Proximal tubular reabsorption ability</p> Signup and view all the answers

    What is the primary focus when assessing renal function through urinalysis?

    <p>Observations must be made on a freshly voided sample</p> Signup and view all the answers

    What is the significance of a Neutrophil gelatinase-associated lipocalin (NGAL) level exceeding normal ranges shortly after injury?

    <p>It serves as an early predictor with prognostic value for kidney injury.</p> Signup and view all the answers

    Which urinary index indicates a tubular injury when its value is greater than 14?

    <p>Urea or Creatinine ratio</p> Signup and view all the answers

    Which of the following conditions would not lead to the increased expression of Kidney Injury Molecule 1 (KIM-1)?

    <p>Chronic kidney dysfunction</p> Signup and view all the answers

    What defines Acute Kidney Injury (AKI) concerning serum creatinine levels according to KDIGO guidelines?

    <p>Increase in Serum Creatinine by &gt;26.5 µmol/l within 48 hours.</p> Signup and view all the answers

    Which statement about IL-18 is correct in the context of acute kidney injury?

    <p>IL-18 can indicate systemic stress unrelated to kidney injury.</p> Signup and view all the answers

    Which of the following is true regarding the protein L-FABP in the context of renal injury?

    <p>L-FABP can indicate tubular injury as a result of fatty acid metabolism.</p> Signup and view all the answers

    What role does acid-base status play in the evaluation of pre-renal acute kidney injury (AKI)?

    <p>It depends on the type of fluid loss, such as vomiting or diarrhea.</p> Signup and view all the answers

    In the evaluation of acute kidney injury, what would be a misleading indicator?

    <p>Unchanged nephron integrity without external factors.</p> Signup and view all the answers

    Study Notes

    Diagnostic Evaluation

    • The clinical context, history, and physical examination can help determine the cause of AKI

    Pre-Renal Azotemia

    • Clinical Setting: Blood loss, Vomiting, Diarrhea, Glycosuria causing polyuria, Drugs
    • Physical Signs: Orthostatic hypotension, Tachycardia, Reduced jugular venous pressure, Decreased skin turgor, and Dry mucous membranes

    Intrinsic Renal

    • History: Suggestive of progression from Pre-Renal AKI (Ischaemic Spectrum) Exposure to specific Nephrotoxins
    • Drug Doses Must be adjusted for GFR- Idiosyncratic reactions may occur
    • Signs: Palpable Purpura, Pulmonary Hemorrhage → Systemic Vasculitis with Glomerulonephritis, Livedo reticularis, and other signs of emboli to the legs → Athero-Embolic disease, Signs of limb ischemia may suggest rhabdomyolysis

    Post-Renal AKI

    • History: Prostatic disease, nephrolithiasis, or pelvic or para-aortic malignancy
    • Symptoms: Ureteric Obstruction → Colicky flank pain radiating to the groin, Prostatic Disease → Nocturia, Urinary Frequency or Hesitancy, Bladder enlargement → Abdominal fullness and suprapubic pain
    • Diagnosis: Requires radiologic investigations

    Biochemical Tests of Renal Function

    • Assessment of Renal function should start with examination of the Urine
    • Simple observation still contributes to the investigation
    • Observations must be made on a freshly voided sample
    • Diseases affecting the kidneys can selectively damage glomerular or tubular function
    • Isolated disorders of tubular function are relatively uncommon
    • In Acute Kidney Injury, there is a loss of function of whole nephrons
    • Tests of Glomerular function are invariably required

    Principal Functions

    • Glomeruli: Filter water, Filter Low Molecular Components, Retain High Molecular Components, Retain Cells
    • Tubules: Reabsorption of Glucose, K, Na, Bicarbonate, Amino Acids, Reabsorption of Water → Urine concentration ability, Acid-Base Regulation

    Assessment of Glomerular Integrity

    • GFR or Equivalent Tests: Urea, Creatinine, Cystatin C
    • Glomerular Filtration Barrier Integrity: Proteinuria, Haematuria (Red Blood Cells), Red Cell Casts

    Assessment of Tubular Integrity

    • Tests: Glycosuria, Amino Aciduria, Proximal Tubular Reabsorption Ability, Acid-Base Regulation, Renal Concentrating Ability → Osmolality

    Urinalysis

    • Volume: Reduction in urine output usually denotes more severe AKI and is associated with a poorer prognosis
    • Oliguria: This is due to tubular injury and resultant inability to reabsorb sodium
    • Osmolality: The urine concentrating ability of the kidney is dependent upon many factors, Adequate tubular function in multiple regions of the kidney is vital
    • Pre-Renal AKI : Urine Osmolality > 500 mOsm/kg This is consistent with: an intact medullary gradient and elevated serum vasopressin levels causing water reabsorption resulting in concentrated urine
    • Renal AKI : Urine Osmolality < 350 mOsm/kg Due to loss of concentrating ability
    • Urine Osmolality: Serum Osmolality
      • Pre-Renal AKI: Urine Osmo : Serum Osmo > 1.3
      • ATN: Urine Osmo : Serum Osmo < 1.3
    • Summary of Diagnostic Tests:
      • Urine Microscopy: + Hyaline casts (Pre Renal), Muddy brown Coarse granular casts, free renal tubular cells (ATN)
      • Spot Urine Na: < 20 mmol/L (Pre Renal) , > 20 mmol/L (ATN)
      • FENa: 2 % (Pre Renal), > 3 % (ATN)
      • Serum Urea: > 70 (Pre Renal), Usually “normal”
      • Urine: Serum Osmolality > 1.3 (Pre Renal), <1.3 (ATN)

    Novel Biomarkers

    • Neutrophil gelatinase-associated lipocalin (NGAL):
    • Protein expressed by neutrophils and epithelial cells
    • The encoding gene is upregulated in the presence of renal ischemia, tubule injury, and nephrotoxicity. Measured in plasma and urine.
    • Useful early predictor with prognostic value
    • Kidney Injury Molecule 1 (KIM-1): Transmembrane protein, Abundantly expressed in proximal tubular cells injured by ischemia or nephrotoxins
    • Other Biomarkers: IL-18 (Interleukin), Liver fatty acid–binding protein (L-FABP), Tissue inhibitor metalloproteinase inhibitor 2 (TIMP-2), Insulin growth factor– binding protein 7 (IGFBP7)

    AKI Diagnosis (KDIGO)

    • AKI is defined as any of the following:
      • Increase in Serum Creatinine by >26.5 mol/l within 48 hours; or
      • Increase in Serum Creatinine to >1.5 X baseline, which is known or presumed to have occurred within the prior 7 days; or
      • Urine volume ↓ excretion of acids, Impaired H secretion & Regeneration of HCO3, Reduced ammoniagenesis

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    Acute Kidney Injury and Laboratory Investigations Part II PDF

    Description

    Test your understanding of diagnostics related to Acute Kidney Injury (AKI). This quiz covers the clinical context, physical examination signs, and the distinctions between pre-renal, intrinsic, and post-renal causes. Assess your knowledge and improve your clinical skills in nephrology.

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